line 897 throws the error : The variable $localPath is wrong as that is what makes it look for the required file in wrong location.

ResourceLoaderFileModule-snippet

protected function readStyleFile( $path, $flip, $context = null ) {
                $localPath = $this->getLocalPath( $path );
                $remotePath = $this->getRemotePath( $path );
                if ( !file_exists( $localPath ) ) {
                        $msg = __METHOD__ . ": style file not found: \"$localPath\"";
                        wfDebugLog( 'resourceloader', $msg );
                        throw new MWException( $msg );
                }

public function getStyleFiles( ResourceLoaderContext $context ) {
return array_merge_recursive(
self::collateFilePathListByOption( $this->styles, 'media', 'all' ),
self::collateFilePathListByOption(
self::tryForKey( $this->skinStyles, $context->getSkin(), 'default' ),
'media',
'all'
)
);
}